Valve tappet and method of forming the same



W. C. OSTERHOLM VALVE TAPPET AND METHOD 0F FORMING THE SAME Nv.- 29,1927..l

Filed April 2l. 1924 lil WILLIAM C. OSTERHOLIVI, 0F OAK SPARK, LLIOIS,ASSIGNOR TO WILCOX PRODUCTS CORPORATION, 0F SAGINAW, MICHIGAN, ACORPORATION 0F MICHIGAN".

. L VALVE TAPPETI AND METHD @E FURIVHNG; THE SAME.

Application led April 21, 192e.: Serial No. 708,04l.

The invention relates tu valve lifters'or tappets and has tor itsobjects; rst, reduc tion in the costv of manufacture; second, theobtaining of a light durable structure; third, various other advantagesas hereinafter set forthi ln t-he drawings:

Figure l illustrates the blank from which the tappet head is formed;

Figures 2 and 3 are cross sections showing successive steps in theforming of the head; l

Figure d is an elevation of the blank from which the stein is formed;

Figure 5 is a stem formed from the blank;

litigare t is an enlarged section illustrating the manner of securingthe stem to the head;

Figures 7 and 8 are sectionsshowing moditied constructions ot stem; I

Figure 9 is a section through the stem and head showing anothermodification; A

Illigures l0 and ll are sections showing successive steps inthemanufacture ot the Vennstrnction of Figure 9.

lt is the primary object oi the invention to separately torni the headand stem ot the tappet, this permitting both of economy in the use olimaterial andthe selectionL oi" qualities best suited for the respective'parts. the manufacture et tappets it is usual to form the same ot singleblanksy which may he either forged, cast or formed in various Ways. IThevarious operations -re quired in the nishing of these lblanks are suchas to involve a considerable cost in manufacture, and the fact that thestructure is all el one material precludes theselection et specialqualities tor diderent portions thereof. For instance, the head, whichis subjected to the Wear ofthe cam, needs a hardenc-id bearing surface,While the stem is stronger and'better it left comparatively soft.. rlhediilerence in hardness may be se-d cured by suitably controlled heattreatment, but this adds to the complexity and cost of manufacture.

lrlleretotore certain constructions ol tap pets have been made fromseparate blanks, but such structures tor various reasons have not provenaltogether satisfactory and diiiiculty is experienced in securelyuniting the head ot the stem. With my improved structure this diculty isentirely eliminated and the resulting structure is superior to thoseformed from the single blank.

As shown in Figures l to 6, the method of manufacturing my improvedtappet is as follows: A round disk blank of sheet metal A is fashioned,preferably by a coining press, to form a recess B, as shown in ligure Q.The annular Walls ot this recess are undercut, as shown in Figure 3, andthe tace of the recess is preferably curved, as shown, :tor the purposehereinafter described. The blankniay be formed of selected material andafter iashioning may be given suitable heat treatment to secure theproper degree ot hardness.

The stem may be formed in various Ways, but as shown in Figure d theblank D isa suitable length or round bar metal.. yl"his blank is thenbored to form apertures ot diderent diameters at the opposite ends, thesmaller aperture lll being threaded to receive the usual adjustmentscrew. This end of the blank may also lbe pressed or other- Wisefashioned into a polygonal tmorm to produce a Wrench hold. 'The largerbore l? is ot such adiameter as to reduce the Walls to the requiredthickness. The end of the tube is then tlared, as shown at G, bypressing in suitable dies, or by other means, so as to torni an obliqueHarige ot a diameter slightly less "than the diameter ol 4the recess ld.

"lhe head and stein are united by endrrise pressure, Whichresults inturning the oblique dange Gr into a plane substantially perpendicular tothe axis of the stem and thereby expanding the diameter so as to forcethe outer edge against the undercut annular Wall into interlockingengagement therewith. rlhis interlocking is facilitated by the anguiarmovement of the flange G which expands the lower portion thereof to agreater diameter than the upper portioncontorming to the shape of theWall. Also, by curving the bottom of the recess as shown atl-l, thedange oii the stem will ,be conformed thereto Without forming a sharpbend. Still another advantageous edect is that the inward pressure otthe annular Wall C, which resists the expansion oil the Harige G, Willtorce the adjacent portieri ofthe tube slightly inward, resulting in aclearance groove lt. 'lhus when soV ' during the pressing operation..

I conical face P to produce the the stem is subsequently groundormachined for engagement with the guide bearing, this clearance groovewill avoid necessity of grinding or machining immediately adjacent thehead.

The structure formed as just described is one where there will be notendency for.the head to separate from the stem as these parts are rmlyinterlocked. Furthermore, there is a constant outwardtension on theiange G, due to the resiliency of-the metaland the fact that theadjacent portion of the tube has been slightly contracted in diameterThe chamber within the stem may be used asa lubricant container and Ihave therefore Afashioned the central portion of the recess of cup form,as shown at J, with a central aperture. K for feeding the lubricantdirectly onto the cam.

As has been stated, the stem may be ormed'in lvarious ways, such forinstance as by any of the usual methods of drawing a tube from a sheetmetal blank. During this drawing operation the flared ange at the end ofthe blank is easily formed so as to be ready for engagement witha headin the manner previously described. Where, however, the blank is madefrom sheet metal, the walls are of substantially uniform thickness andit may be necessary to provide a bushing for the threaded end. Thisbushing Lmay be formed as shown in Figure T with a peripheral groove Minto which the tube is pressed by rolling or other suitable means,effecting the interlocking engagement. Figure 8 ,shows a cupped bushingL for receiving t valves, said bushing being similarly locked to thestem.

' In Figures 9, l10 and 11 a furtherl modification is shown wherein atube of uni' form diameter is expanded by endwise pressure to engage andinterlock with an oblique annularslot N in the head. With-thisconstruction the head O may first be formed as shown in Figure Psurrounded by a an e Q, parallel to the axis. v The ange Q, is t encompressed and forced inward into parallelism with the oblique slot N.

With all of thevarlous modifications the stem is interlocked with thehead by the expansion thereof due to endwise pressure. Also thisoperation is performed after the completion, including the heattreatment, of the head so that there is no necessity of any furtherlheat treatment 4or any operation which might tend to loosenthe joint.

When the is pressed intol a plane perpendicular" to the axis, there issome danger of concentrating the stresses at the bend and overstrainingthe metal. Such an effect I have avoided by first forming the flaringportion,`- as Y' portion and a heppush rod of overhead' 10 with aconical face flaring end portion of the stem said stem member with anoutwardly Haring shown specifically in Figure 5. It will be noted thatas thus formed the portion irnmediately adjacent to the cylindricalportion of the stem is initially bent to approximately the planeperpendicular to the axis, while the outer portion is oblique to theaxis. With such a form the pressure applied to expand the stem into thehead will only react on the flaring outer portion thereof and will notconcentrate any bendin stress at the angle between the cylindrical partand the fiange; also, as the metal is chiefly in tension, it will bedrawn wit-hout fracture. Still further, the portion adjacent to thelower surface of the flange will be expanded to a greater extent thanthe upper surface thereof so as to fill the undercut portion of therecess in the head.

What I claim as my invention is: 1'. The method of manufacturing tappetscomprising the separate forming of a head member and a tubular stemmember, said stem member having an annular end portion which isrelatively oblique to asurface on said head member and said head memberbeing undercut adjacent to said surface, and applying endwise pressureto said members to turn the end portion of said stem member and to forcethe same into interlocking engagement with the undercut portion of saidhead member.

2. The method of manufacturing tappets comprising the separateformingrof a head member and a tubular stem member, said head memberbeing provided with an undercut surface adjacent thereto which isrelatively oblique to an annular end portion of said stem' member, andapplying endwise pressure to said members to turn the end of said stemmember by the relatively oblique portion of said head member and intointerlocking engagement with the undercut `portion thereof.

to said members'to outwardly bend the end portion of said stem memberand to force the same intointerlocking engagement with said annularundercut portion,

' 4. The method of manufacturing tappets comprising the separate formingof a head member and a tubular'stem member, said head' member beingprovided with an annular radially outwardly undercut portion and saidflaring portion into'parall'elism with the lll) Leeoae adjacent surfaceof said head and to thereby expand the same into interlocking engagementwith said undercut portion.

5. rlhe method of manufacturing tappets comprising the separate formingof a disk head and a tubular stein, said head being provided with anannular radially outwardly undercut portion and said stein with anoutwardly-lared annular end portion non-parallel to thel adjacentsurface of said head,

and applying endwisepressure to said members to bend the end portion ofsaid stem.k

into parallelism with said head and thereby to peripherally interlockundercut portion.

6. The method of manufacturing tappets' the same with lsaid comprisingthe separate fashioning of a diskf h'ead member and a tubular stemmember, said head member being provided with an annular radiallyoutwardly undercut shoulder and a curved surface adjacent thereto, saidstem being provided with a flaring annui lar end portion non-parallel tosaid curved portion on saidhead, and applying end- Wise pressure to saidmembers tobend the flaring portion of said stem into parallelism withthe curved portion of said head and to thereby peripherally expand thestem into interlocking engagementwith said undercut shoulder.

7. The method of manufacturing tappets comprising the se arate formingof ahead Amember and a tu ular .stem member, said stem member beingfashioned with a flaring annular end portion which in its outer part ismore oblique to the axis of the stem than in the part immediatelyadjacent to the stem,

' said head being provided with an annular undercut portion, andapplyingend pressure to said members to bend the oblique portion of said stemand to peripherally-expand the same into interlocking engagement withthe undercut portion of said head.

8. The method of manufacturing tappets comprising the separate formingof a head memberand a tubular stem member, said stem member beingfashioned with a Haring annular end portion which adjacent .to the bodyportion thereof is substantially in a plane perpendicular to the axisand is more obliqueto the axis in its outer portion, said" head beingprovided `with an annular undercut shoulder of sulicient minimumdiameter to receive the Haring portion of said stein and in applyingendwise lpressure to said membersto bend the oblique portion of saidstemsubstantially into a plane perpendicular to the axis and thereby.force the same into interlocking engagement with said annular undercutshoulder.

9. The method of manufacturing tappets comprising the separate formingof a headl member` and a tubular stein member, said stem member beingbfashioned with walls of greater thickness at one end thereof and with aflaring annular portion at the oppositeend thereof and said head beingprovided with 'an undercut annular shoulder of a minimum diameter`sufficient to receive said flaring portion, and in applying end pressureto said members to peripherally expand said flaring portion of the stemand to force the same into interlocking engagement with said annularundercut portion of the head.

l0. A tappet comprising a one piece head member recessed to form abottom surface and an annular undercut shoulder, and a tubular .stemmember lprovided with a ilarling end portion engaging said recess andinterlocked with said undercut shoulder, said flaring end:I portionalsohaving its .lower surface contacting for its entire length with thebottom surface of said recess. n

11A tappet comprising a head member recessed to form an annularshoulder, and `a tubular stein member provided with an annular flange atone end thereof extending substantially in a plane perpendicular to theaxis and interlocked with said annular shoulder.

' 12. A tappet comprising a' head recessed to form an annular shoulderand With a curved surface tangent to the bottom of said recess and atubular stem having an annular flange at one end thereof rounded to lieagainst said curyed surface of the head and with an outer portionsubstantially in a plane perpendicular to the axis of the stem andVinterlocked with said shoulder. .Y 13. A tappet comprisingl a headrecessed to form a bottom surface and an annular -undercut shoulder, anda tubular stem-having an annular flange extending substantially in aplane perpendicular to the axis of the stem, said flange having itslower surface engaging the bottom surface of said recess and having itsouter annular edge interlocked with said undercut shoulder.l

to said Harige being of slightly less radiusl than the tubular portion.

15. A tappet comprising a head recessed to form an annular radiallyundercut shoulder with an inwardly extending curved surface tangent tothe bottom of the recess and a tubular stem provided with an annular Hane extending substantially in a plane perpen icular to the axiswith itsperiphery interlocked-with said undercut shoulder and the portionintermediate said peripheral Y portipn andthe body portion curved to fitlthe, curve of `said 4head 'and reinforced thereby.

P 16. A tappet comprising a disk head reisc cessed to form an annularundercut shoulder with an inwardly extendingcurved surface of sald headand the central recess drainling the lubricant within the stem towardssaid central aperture. Y Y

17. A tappet comprising a disk head recessed to form an annular shoulderand a tubular stem having thickened walls at one end thereof and apolygonal exterior, the opposite end of said stem being provided withanannular fiange extending substantiall in a plane perpendicular to theaxis of t e stem and interlocked with said annular shoulder, the portionof said stem immediately adjacent to said iange being pressed radiallyinward to form a slight groove.

18. The method of manufacturing valve tappets comprising the separateforming of a disk head and a tubular stem, said head being recessed toform an annular undercut shoulder and said stem being provided at oneend with an annular Haring portion initially oblique to the axis of thestern, and in' applying endwisel pressure to said members to bend saidflaring portion substantially into a plane perpendicular to the axis ofthe stem, thereby peripherally ex anding the same into engagement withsai( undercut recess, the lower portion being expanded to a greaterextent than the upper portion to fill .the undercut of the recess.

` In testimony whereof I afx my signature.

WILLIAM C. OSTERHOLM.

